Grantee Research Project Results
Final Report: Using bioindicators to develop a calibrated index of regional ecological integrity for forested headwater ecosystems
EPA Grant Number: R825866Title: Using bioindicators to develop a calibrated index of regional ecological integrity for forested headwater ecosystems
Investigators: Brooks, Robert P. , Mulvihill, Robert S. , Master, Terry L. , OConnell, Timothy J. , Laubscher, Susan E.
Institution: Pennsylvania State University , East Stroudsburg University of Pennsylvania , Powdermill Nature Reserve
EPA Project Officer: Packard, Benjamin H
Project Period: June 1, 1998 through May 31, 2001 (Extended to September 30, 2002)
Project Amount: $850,000
RFA: Ecosystem Indicators (1997) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
Forested headwater streams comprise 60-75 percent of the total stream length and watershed area in the Mid-Atlantic Highlands (MAH) and are impacted by a variety of environmental stressors. Given the cumulative importance of headwaters to the ecological integrity, recreational quality, and food production of riparian and estuarine ecosystems throughout the region, the objective of this project is to develop an index that managers and decisionmakers can use easily and confidently to target protection and restoration efforts.
We investigated the potential of using bird and macroinvertebrate communities as bioindicators of environmental stressors that affect forested headwater streams in the Pennsylvania portion of the MAH. Our objective was to construct a Regional Index of Biological Integrity (RIBI) for these critically important aquatic habitats. We used a stressor-response approach to explore relationships between the biological communities (y-axis) and physico-chemical stressors (x-axes). Our study area in Pennsylvania included 23 stream reaches in 3 study subareas representing 3 ecoregions and 3 major drainage basins that extend into several states in the MAH. Specifically, we examined the responses of the biota to three primary stressors: habitat fragmentation (represented by percent forest in 1-km radius circles), acidification (low pH caused by either acid deposition or coal mine drainage), and an amalgamation of sedimentation, eutrophication, and hydrologic modification (represented by Stream Habitat Assessment [SHA] scores). We included three types of bioindicators: Louisiana Waterthrush (LOWA) and other riparian songbirds, songbird communities, and stream macroinvertebrate communities.
We examined the response of these bioindicators to these primary stressors. The end result was the development of a Headwater Stream Assessment (HSA) index that uses simple measures of landscape, stream habitat, and instream water chemistry to characterize the condition of headwater streams. Those applying the HSA to streams in the region have the option of implementing Index of Biological Integrity (IBI) for birds or macroinvertebrates to help diagnose local stressors. Figures 1 and 2 illustrate the study area and sampling design.
Figure 1. Location of 23 Study Stream Reaches in 3 Major River Drainages of Pennsylvania
Figure 2. Schematic Representation of Sampling Design at a Hypothetical Study Reach. For most sites, we focused on data collection within a 2-km riparian corridor. In this corridor, we collected data on water chemistry, benthic macroinvertebrates, breeding birds, and vegetation, and applied SHA and habitat suitability index (HSI) models to systematic random sampling locations. Observation, monitoring, and banding of LOWA, and territory mapping of riparian songbirds occurred anywhere along the sample reach to a distance of approximately 50 m on either side of the stream channel. Land cover data were analyzed within a 1-km radius circle and throughout the 14-digit hydrologic unit code (HUC) boundary of the local watershed.
Summary/Accomplishments (Outputs/Outcomes):
The final products of our research include: (1) a simple approach to assessing condition of forested headwater streams based on easily measured physico-chemical metrics (HSA); (2) calibration of that approach against a set of biological parameters; and (3) a series of submitted and/or proposed papers that explain these findings in detail.
Although we do not recommend use of a single RIBI with the HSA, we have developed a simple and efficient approach that both addresses an ecological integrity gradient and spans spatial scales. The HSA we developed meets all six principles of RIBI development outlined in the introduction of our full progress report. We recommend that the HSA be applied as follows:
1. Small watersheds (14-digit HUC or smaller) are assessed by determining the percent forest cover in 1-km radius circles, which are located at the midpoint of each 2-km reach along the headwater streams being investigated. For the Mid-Atlantic Highlands Assessment Program (MAHA), we have found that the single landscape metric of percent forest is sufficient to measure deviation in condition from reference. The metric thresholds for categories of high, medium, and low forest cover are shown in Table 1:
Table 1. The Metric Thresholds for Categories of High, Medium, and Low Forest Cover
| Forest Cover | ||||
|---|---|---|---|---|
| <40% | 41 - 70% | 71 - 100% | ||
| Bird Community Index (BCI) ecological integrity category | low - medium | medium - high | high - highest | |
| Metric Rank | 1 | 2 | 3 | |
Figure 4. Simple Linear Regression of BCI Score on Percent Forested Land Cover in 314 ha Circles. The proportion of forested cover in surrounding local landscapes is significantly associated with ecological integrity modeled by the BCI and with the occurrence of LOWA breeding territories.
2. We recommend that the SHA be conducted at 5 points per 1 km. Each SHA takes about 10 minutes once on site, and produces a score between 0 and 200. Based on this study, we present the thresholds for four levels of condition. Individual metrics contained within the overall SHA can be useful for diagnosing the impact of various stressors.
Table 2. The Metric Thresholds for Categories for Four Levels of Condition
| SHA | |||||
|---|---|---|---|---|---|
| < 125 | 125 - 150 | 150 - 165 | > 165 | ||
| Stream Condition Index (SCI) assessment of macroinvertebrate community | degraded | probable degradation | possible degradation | no degradation | |
| Metric rank | 1 | 2 | 3 | 4 | |
Figure 6. SCI (Y-axis) Plotted Against Mean SHA for Eastern Sample Stream Reaches
3. A measure of pH (calibrated, hand-held electronic meter) is taken at the center point of each SHA station. The literature describing the impact of low pH, acidity, and acid mine drainage on stream biota is extensive. In this study, we found thresholds of pH for determining probable stream condition.
Table 3. The Metric Thresholds of pH for Determining Probable Stream Condition
| pH | |||||
|---|---|---|---|---|---|
| < 4.50 | 4.51 - 5.50 | 5.51 - 6.50 | > 6.50 | ||
| SCI assessment of macroinvertebrate community | severely degraded | moderately degraded | some degradation | no degradation | |
| Metric Rank | 1 | 2 | 3 | 4 | |
Figure 8. SCI Scores for Three Groups of Sites With Different Mean pH Values in the Central and Western Study Areas
4. If a particular stressor is suspected or if a selected stream warrants additional scrutiny, data for any one of the IBIs can be collected. For example, if the percent forest is high, SHA score is moderate, and pH is circumneutral, it may be necessary to collect macroinvertebrates for the SCI to determine how that community is being impacted, if at all, by the stressors addressed by the SHA. Also, assessors can collect data on riparian birds, including LOWA.
Table 4. The Metric Thresholds for Four Levels of Condition, To Determine How Communities are Impacted
| LOWA | 0 | 0 - 1 | 1 - 2 | > 2 | LOWA territories/km |
|---|---|---|---|---|---|
| Riparian Songbirds | 0 | 1 - 4 | 5 - 8 | > 8 | territories/km |
| Riparian Songbirds | 0 | 1 - 3 | 4 - 7 | > 7 | species richness |
| Riparian Songbird community assessment | degraded | probable degradation | possible degradation | no degradation | |
| Metric Rank | 1 | 2 | 3 | 4 |
Table 5. Distribution and Reproductive Output of LOWA Across all Study Regions and Years
| Region | # Sites | # Territories | # Nests | Mean Clutch Size | Territories/km | Nests/km | Fledglings/km |
| East | 6 | 91 | 74 | 4.7 | 2.3 | 2.0 | 5.6 |
| Central | 7 | 49 | 31 | 4.7 | 1.1 | 1.9 | 2.7 |
| West | 10 | 148 | 117 | 4.8 | 1.8 | 1.7 | 7.4 |
| Totals | 23 | 288 | 222 | * | * | * | * |
| Averages | * | * | * | 4.7 | 1.7 | 1.9 | 5.2 |
Figure 10. Fitted Line Simple Linear Regression With 95 Percent Prediction Intervals Illustrating the Relationship Between the Mean Number of LOWA Territories/km and the Mean Number of Fledglings Produced/km.
Table 6. Daily Survivorship Estimates and Sources of Nest Failure. "Mayfield Total" is an estimation of the probability of survivorship of individual eggs in a nest through laying, incubation, and nestling periods.
| Region | Mayfield Total | # Depredated Nests | # Parasitized Nests | # Females Killed on Nest |
| East | 0.64 | 26 (35%) | 5 (7%) | * |
| Central | 0.76 | 7 (23%) | 0 (0%) | 4 (13%) |
| West | 0.55 | 34 (29%) | 3 (3%) | 8 (7%) |
| Totals | * | 67 (30%) | 8 (4%) | 12 (8%) |
| Averages | 0.65 | * | * | * |
Figure 11. LOWA Territories/km (y-axis) Plotted Against Landscape Level Forest Cover for all 23 Sample Reaches.
Figure 12. LOWA Territories/km (y-axis) Plotted Against Mean SHA Score for 16 Stream Reaches in the Eastern and Western Study Areas.
Figure 13. Mean Number of LOWA Fledglings Produced/km (y-axis) Plotted Against Mean pH (x-axis) for 16 Stream Reaches in the Eastern and Western Study Areas.
Figure 14. Riparian Songbird Species Richness (y-axis) Plotted for Three Groups of Sites With Different Mean SHA Scores. Mean SHA scores/group are 1 (112), 2 (161), and 3 (179).
HSA Conclusions. We developed a CSI for the HSA ranging from 0-1 that facilitates comparisons among streams, and provides the flexibility to include metrics related to riparian songbird and LOWA as an optional 4th level:
HSA Indicator Score = Σ (L1-L3) x 3-1 (minimum model)
HSA Indicator Score = Σ (L1-L4) x 4-1 (optional 4-level model).
The regional index proposed here can be broadly applied throughout the region by citizens and environmental managers under the direction of organizations such as the Canaan Valley Institute and The Nature Conservancy. This index can focus attention on the ecological functions (e.g., biodiversity) and economic values (e.g., water supply, ecotourism) of forested headwater streams and their contributing watersheds that comprise about three-quarters of the land area of this region. Thus, the ecological indicators contained in the HSA developed during this research project are applicable throughout the 168,420 km2 MAHA encompassing portions of three major river basins and four states. Although we do not recommend use of a single RIBI, we have developed a simple approach that both addresses an ecological integrity gradient and spans spatial scales.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 39 publications | 1 publications in selected types | All 1 journal articles |
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| Type | Citation | ||
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Mulvihill RS, Cunkelman A, Quattrini L, O’Connell TJ, Master TL. Opportunistic polygyny in the Louisiana Waterthrush. The Wilson Bulletin 2002;114(1):106-113. |
R825866 (Final) |
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Supplemental Keywords:
Louisiana Waterthrush, LOWA, Seiurus motacilla, Headwater Stream Assessment, HSA, Stream Condition Index, SCI, Bird Community Index, BCI, Stream Habitat Assessment, SHA, Mid-Atlantic Highlands, MAH, macroinvertebrate, avain, ecosystem indicators, ecological integrity., RFA, Scientific Discipline, Water, Geographic Area, Ecosystem Protection/Environmental Exposure & Risk, Water & Watershed, Ecosystem/Assessment/Indicators, Ecosystem Protection, State, Ecological Effects - Environmental Exposure & Risk, Monitoring/Modeling, Ecological Risk Assessment, Watersheds, Ecological Indicators, bioindicator, forested headwater ecosystems, landscape indicator, stressors, avian productivity, biodiversity, macroinvertebrates, ecosystem indicators, regional scale, Louisiana (LA), aquatic ecosystems, water quality, forested watershedProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.